libbpf: Fix potential multiplication overflow

Detected by LGTM static analyze in Github repo, fix potential multiplication
overflow before result is casted to size_t.

Fixes: 8505e8709b5e ("libbpf: Implement generalized .BTF.ext func/line info adjustment")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200904041611.1695163-2-andriin@fb.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 53be32a..550950e 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5802,7 +5802,7 @@ static int adjust_prog_btf_ext_info(const struct bpf_object *obj,
                /* append func/line info of a given (sub-)program to the main
                 * program func/line info
                 */
-               old_sz = (*prog_rec_cnt) * ext_info->rec_size;
+               old_sz = (size_t)(*prog_rec_cnt) * ext_info->rec_size;
                new_sz = old_sz + (copy_end - copy_start);
                new_prog_info = realloc(*prog_info, new_sz);
                if (!new_prog_info)